tailieunhanh - Báo cáo khoa học: Nop53p, an essential nucleolar protein that interacts with Nop17p and Nip7p, is required for pre-rRNA processing in Saccharomyces cerevisiae

In eukaryotes, pre-rRNA processing depends on a large number of non-ribosomal trans-acting factors that form large and intriguingly organized complexes. A novel nucleolar protein, Nop53p, was isolated by using Nop17p as bait in the yeast two-hybrid system. Nop53p also interacts with a second nucleolar protein, Nip7p. A carbon source-conditional strain with the NOP53coding sequence under the control of theGAL1promoter did not grow in glucose-containing medium, showing the phenotype of an essential gene. . | iFEBS Journal Nop53p an essential nucleolar protein that interacts with Nop17p and Nip7p is required for pre-rRNA processing in Saccharomyces cerevisiae Daniela C. Granato1 Fernando A. Gonzales1 Juliana S. Luz1 Flavia Cassiola2 Glaucia M. Machado-Santelli2 and Carla C. Oliveira1 1 Department of Biochemistry Chemistry Institute University of Sao Paulo Brazil 2 Department of Cellular and Development Biology Institute of BiomedicalSciences University of Scio Paulo Brazil Keywords rRNA processing nucleolus ribosome synthesis Saccharomyces cerevisiae pre60S Correspondence C. C. Oliveira Departamento de Bioquimica Instituto de Química USP Ave Prof Lineu Prestes 748 Sao Paulo SP 05508-000 Brazil Fax 55 11 3815 5579 Tel 55 11 3091 3810 ext 208 E-mail ccoliv@ Received 12 February 2005 revised 1 July 2005 accepted 12 July 2005 doi In eukaryotes pre-rRNA processing depends on a large number of non-ribosomal trans-acting factors that form large and intriguingly organized complexes. A novel nucleolar protein Nop53p was isolated by using Nop17p as bait in the yeast two-hybrid system. Nop53p also interacts with a second nucleolar protein Nip7p. A carbon source-conditional strain with the NOP53 coding sequence under the control of the GAL1 promoter did not grow in glucose-containing medium showing the phenotype of an essential gene. Under nonpermissive conditions the conditional mutant strain showed rRNA biosynthesis defects leading to an accumulation of the 27S and 7S pre-rRNAs and depletion of the mature 25S and mature rRNAs. Nop53p did not interact with any of the exosome subunits in the yeast two-hybrid system but its depletion affects the exosome function. In pull-down assays protein A-tagged Nop53p coprecipitated the 27S and 7S pre-rRNAs and His-Nop53p also bound directly rRNA in vitro which is consistent with a role for Nop53p in pre-rRNA processing. The factors involved in rRNA processing in eukaryotes assemble .